1. Field of the Invention
The invention relates to an optical device and an adjusting method thereof, and particularly relates to a light source device and an adjusting method of the light source device.
2. Description of Related Art
An interactive projection system is a projection system that allows the user to perform a touch operation on a projection plane. In the interactive projection system, an invisible light (e.g. infrared light) curtain emitted from a light source device ranges over the whole projection plane. Therefore, the invisible light curtain may be reflected by a touch object (e.g. the user's finger or a stylus) to generate a reflected light beam when the user performs an interactive touch operation to a projected image on the projection plane, thereby using an invisible light detecting device to receive the reflected light beam and detect a touch position. Thus, a corresponding touch signal may be generated.
The distance between the invisible light curtain and the projection plane may influence the touch operation. Specifically, if the distance between the invisible light curtain and the projection plane is overly long, the touch object (e.g. the user's finger or a stylus) may be present in a region between the invisible light curtain and the projection plane when the user performs the touch operation on the projection plane, such that the light detecting device may detect an incorrect touch position and generates an unexpected touch signal. Namely, a touch sensitivity is overly high. On the contrary, if the distance between the invisible light curtain and the projection plane is overly short, the touch object may easily block the reflected light beam when the user performs the touch operation on the projection plane, thus, the light detecting device is unable to detect the touch position and generate the touch signal. Namely, the touch sensitivity is overly low. Therefore, the distance between the invisible light curtain and the projection plane needs to be appropriately adjusted so that the touch may be input normally.
A conventional method for adjusting the distance between the invisible light curtain and the projection plane is that the distance between the invisible light curtain and the projection plane is determined and adjusted by using a single visible light beam coinciding with the invisible light curtain. However, such method only provides the distance between the single visible light beam and the projection plane, and the distances between other positions of the invisible light curtain and the projection plane are unable to be determined by the method whether the distances are adjusted appropriately or not. In other words, the conventional adjusting method is not able to make the invisible light curtain completely and precisely parallel to the projection plane.
China patent publication no. 102914937A has disclosed a projection system having a touch capability. The projection system is capable of sensing a touch input by an invisible light curtain emitted from a light-emitting module. Three contact elements are disposed on the light-emitting module, such that contacts of the contact elements with the projection plane are used to determine whether the invisible light curtain emitted from the light-emitting module is parallel to the projection plane. US patent publication no. 20110083109 has disclosed an electronic whiteboard system. In the electronic whiteboard system, a visible light beam emitted by a laser positioning sensing unit is configured to determine a distance between a sensing plane thereof and a projecting plane of the whiteboard.